Over the past two games, Red Bulls coach Mike Petke went with a youth movement along his back line, a trio of players who average 21 years old and had a total of seven MLS starts. According to Petke, it was about time.

When Petke got the head coaching job last year, he talked about promoting from within and vowed to give young American players a chance. An unproven rookie coach himself, entrusted with a star-studded, high-priced yet underachieving roster, Petke succumbed to the pressure of playing veterans and getting results.

With a Supporters’ Shield and a contract extension in his back pocket, this year Petke had the cachet to put his money where his mouth was. First came rookie fullback Chris Duvall, then teen-academy product Matt Miazga, and finally young international signing Ambroise Oyongo.

“Last year, I spoke a lot about getting the young players involved, particularly from our academy, for instance Matt Miazga,’’ Petke said. “Perhaps it was one part me being a new coach, and another part along with that was knowing that I’m judged on my results. So it was much easier for me to go with the experienced-type guy. Truth be told, last year it paid off as the regular season goes.

“As a guy that was brought up in this in organization since I was drafted, the one thing that really kept calling me back was that I want this to be a true New York club, a homegrown-type club. I don’t want it to be relying on older, more experienced players that come in every year or two. I want to start somewhere, and start from the bottom and have guys have longevity here, have guys grow up in this club and learn from it and be very identifiable with it.

“Having said that, does that mean next week is going to be a whole new lineup with all young players? I doubt it. But these guys have given me the confidence to really go with my gut when a young player is playing well during the week.’’

With Kosuke Kimura unable to hold down the right back spot and offseason acquisition Richard Eckersley a non-factor, the 22-year-old draft pick Duvall was the first of the youngsters to get the call to start this season. After that came Miazga, a lanky 19-year-old centerback who debuted last year with a 14-minute cameo.

Finally came Oyongo, who signed this offseason from Coton Sport in his native Cameroon and joined Duvall and Miazga in the lineup the last two games against Toronto and Houston — notching assists in both games. He showed nice crossing, blistering pace and flashy dribbling ability.

“Chris Duvall, when he first went in, it was a decision we were thinking about,’’ Petke said. “He was showing all the right signs in practice, and then what transpired in that game in Toronto, we said, ‘Let’s put him in.’ He did well with it, started the next game and continued to do well and that gave me the confidence to put Matt Miazga in who was in a similar boat as well, a guy that we kept saying, ‘We need to get him minutes, we need to see what he can do.’

“So Chris gave me the confidence for that, and then [Matt] took that and he was one of the best players in New England in his first game. That gave me the ability to put a young Oyongo in and he ran it with it as well. There’s definitely some work to be done with getting them up to speed, meshing and gelling together and getting their inexperience and nerves out. Individually, they’ve had some very good moments [and] they’ve had some moments that they can learn from. The good moments heavily outweigh the moments that they’re going to improve on.

“The good thing about those three young men is they’re eager, they’re willing to learn and they want the information and they want to run with this. They’re not taking this opportunity for granted — which is very important, which I’ve relayed to them. They need to have the same attitude every day from this point on that they had leading up to their first start, which is the reason they got that first start.’’